Overview: FISH 11q23 MLL Panel
Introduction: The FISH 11q23 MLL Panel is a diagnostic tool designed to detect MLL gene rearrangements using whole blood or bone marrow samples. In India, MLL (KMT2A) rearrangements occur in ~5-10 percent of acute leukemias (higher in infant ALL ~70-80 percent, adult AML ~5 percent), associated with poor prognosis and specific subtypes (e.g., MLL-AF4, MLL-AF9). High morbidity from under-testing in rural/low-SES leukemia patients, limited FISH labs, delayed targeted therapy or intensive regimens leading to relapse or mortality. Per cytogenetics practices aligned with ICMR and Indian Society of Hematology guidelines, the test employs fluorescence in situ hybridization (FISH) for MLL breakapart over 1-2 days with high sensitivity/specificity, valuable for rapid diagnosis and risk stratification in acute leukemia. This diagnostic falls under genetic cancer screening and targets patients with acute leukemia (especially infants or poor-risk features), addressing accurate detection to guide chemotherapy intensification or clinical trials. With elevated morbidity due to under-testing, the test supports public health efforts by enabling precise molecular classification and improving survival. Its blood/bone marrow-based approach ensures reliable rearrangement detection.
Other Names: FISH MLL Pnl.
FDA Status: FDA approved, CLIA certified for cytogenetics, compliant with 2025 standards.
Historical Milestone: MLL FISH standard; in India, used in leukemia protocols.
Purpose: The test detects 2 parameters including MLL gene breakapart to guide leukemia genetic assessment, identify rearrangements, inform prognosis/therapy.
Test Parameters: 1. MLL Gene Breakapart, 2. Chromosomal Rearrangement.
Pretest Condition: No fasting required; patients should have confirmed acute leukemia.
Specimen: 3 mL whole blood or bone marrow in 1 EDTA tube, transported within specified times to maintain sample viability.
Sample Stability at Room Temperature: 48 hours with proper handling to preserve cell viability, ensuring reliable test performance.
Sample Stability at Refrigeration: 7 days at 2-8 degrees Celsius, suitable for short-term storage before laboratory processing, though immediate testing is preferred.
Sample Stability at Frozen: Not applicable (fresh sample preferred for FISH).
Medical History: Patients should provide details on leukemia subtype, age, WBC count, prior therapy.
Consent: Written informed consent is required, detailing the test's purpose, potential risks of undetected MLL rearrangement including poor prognosis, benefits of detection, and minimal discomfort from blood/bone marrow draw.
Procedural Considerations: The test involves sample processing using FISH by trained personnel to ensure sterile technique, avoid contamination, and interpret results within 1-2 days using provided probes/controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.
Factors Affecting Result Accuracy: Delays beyond stability periods, improper storage conditions, or low blast count can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.
Clinical Significance: Positive MLL rearrangement indicates high-risk leukemia, necessitating specialist input. Negative may require follow-up if features suggestive.
Specialist Consultation: Pediatric/medical oncologists should be consulted for management.
Additional Supporting Tests: Karyotype, NGS for confirmation.
Test Limitations: Detects rearrangement only; comprehensive approach required.
References: Indian Journal of Hematology 2024, Leukemia Studies India 2023.
